1. Field of the Invention
The present invention relates to an image sensing device and an image sensing method thereof, and more particularly to a high-resolution image sensing device and an image sensing method for detecting a motion direction precisely.
2. Description of Related Art
Image sensing device is provided for detecting a motion trajectory to determine the motion of the sensing device or even calculating a motion speed by consecutively detecting images and comparing the sensed images for any change. In the process of determining the motion trajectory, a processing unit installed in the image sensing device is used for sequentially comparing each sensed frame, and thus information such as displacement direction and displacement magnitude can be obtained by repeating the foregoing comparison and computation.
At present, a conventional way of calculating the motion trajectory is to adopt a previous frame and a following frame as base frames and a comparing frame accordingly for comparing an image position. If the comparison indicates no change of image positions in the aforementioned two frames, then the frame (which is the aforementioned previous frame) will be reserved as a base frame for later comparisons, and the comparing frame will be abandoned, and then the next frame will be used as a comparing frame to be compared with the original base frame. If there is a slight change of the image positions of two frames, then the conventional way replaces the original base frame by the current comparing frame as a new base frame. And the new base frame is used for the comparison of the next frame until the change of image positions has reached a threshold, e.g. a displacement of the image position equal to a pixel. This method can calculate a rotation angle or a deviation angle of a moving image sensing device.